The present disclosure relates to a status detection device which includes a heater for heating a toner image transferred onto a paper sheet and detects a status about power supply to the heater. In addition, the present disclosure relates to an image forming apparatus including the status detection device.
An electric apparatus such as an image forming apparatus (e.g. a printer, a multifunction peripheral, a copier, or a FAX machine) operates using electric power supplied from an AC power supply such as a commercial power source. If the power supply to the image forming apparatus is abruptly turned off because of a certain reason such as a power failure or a malfunction, data being processed may be lost. In addition, the sudden turn-off of the power supply may cause a damage to the image forming apparatus. Therefore, in order to detect whether or not the AC power is being supplied from the AC power supply, a zero cross signal may be generated on the basis of a voltage (current) of the AC power supply.
As described below, there is known an image forming apparatus which detects whether or not the AC power is being supplied from the AC power supply on the basis of the zero cross signal. Specifically, there is known an image forming apparatus, in which a power voltage monitoring circuit for monitoring an input of the AC power supply is disposed, the power voltage monitoring circuit detects that power supply to a power supply unit is interrupted, and changes a DCP-REDY signal as a power supply monitoring signal. The power voltage monitoring circuit generates a zero cross signal. Then, if the zero cross signal is not supplied during a predetermined time period (for example, 100 ms), it is determined that the AC input is interrupted, and the DCP-REDY signal is dropped to low level.
As described above, the image forming apparatus may detect power supply from the AC power supply or turn-off thereof (ON/OFF of power supply). In addition, the detection may be performed concerning a plurality of items such as whether or not power is supplied normally from the AC power supply, whether or not an input for stopping power supply to the heater or the like is performed, and whether or not disconnection has occurred in the path from the AC power supply to the heater. In this way, the image forming apparatus may detect a plurality of items concerning status of the image forming apparatus.
In accordance with detection items, sensors and components (elements) for detection are disposed respectively. Then, sensor output values and voltage values near the components are supplied to a control circuit (control portion) such as a CPU. Then, on the basis of the output values or voltage values supplied from the sensors, the control circuit detects or recognizes status of the image forming apparatus concerning a plurality of items.
Here, conventionally, one signal line is used for one sensor or component for detection so as to perform input to a port of the control circuit such as the CPU. For instance, if there are four detection items, four sensors are disposed, and four signal lines are disposed for input from the four sensors to the control circuit. Therefore, the signal lines for input to the control circuit increases along with an increase of the detection items.
Further, when a plurality of items concerning the status are detected as described above, signal lines to be wired in the apparatus may be increased. Therefore, the wiring becomes complicated so that time and effort for wiring are increased. In addition, a large space for wiring in the apparatus is necessary. In addition, a problem concerning manufacturing cost may occur. In addition, because it is necessary to use a control circuit (for example, a CPU) having many input ports, a problem concerning manufacturing cost or flexibility in selecting the control circuit may occur.
Note that the known image forming apparatus described above detects ON/OFF of a power switch by a power switch monitoring switch and detects whether or not the AC power is supplied by the power voltage monitoring circuit, in which one switch or circuit is used for one item to be detected as before. Therefore, in the above-mentioned known image forming apparatus, wiring becomes complicated so that time and effort for the wiring is increased, and it is necessary to secure a large space for the wiring. In addition, it is difficult to solve the problem that manufacturing cost cannot be reduced.